In U.S. Pat. No. 3,232,678 issued Feb. 1, 1966 to William G. Wilson, and assigned to the assignee of the present application, there is shown and described a brake control valve device that is substantially the same in function and operation as the brake control valve device included in the standard fluid pressure brake apparatus now in use on railway freight cars owned and operated by American railroads.
The brake control valve device shown in the abovementioned U.S. Pat. No. 3,232,678 comprises a service valve portion embodying therein a plurality of slide, spool and disc-type valves, and an emergency valve portion that has a slide-type emergency valve slidable on a flat ported valve seat and a graduating valve slidably mounted on a flat ported surface provided therefor on the side of the emergency slide valve opposite the side thereof that engages the flat ported valve seat. This emergency valve portion is operative in response to a service rate of reduction of pressure in a train brake pipe to release fluid under pressure from a quick action chamber to atmosphere at a service rate thereby rendering this emergency valve portion effective to cause an emergency brake application only in response to an emergency rate of reduction of pressure in the train brake pipe.
The manufacture and production of these slide-type valves and valve seats of this emergency valve portion requires considerable accurate and skillful machining which, as is readily apparent, increases the cost of the emergency valve portion of which they are an essential component.
Accordingly, it is the general purpose of this invention to provide a railway car brake control valve device with a novel emergency valve portion that embodies therein a plurality of simple and inexpensive poppet valves of the diaphragm type that are subject opposingly to the pressure of fluid in the train brake pipe and in a quick action chamber, and are operative in response to a service rate of reduction of pressure in the train brake pipe to vent fluid under pressure from the quick action chamber to the train brake pipe at a service rate thereby preventing operation of this emergency valve portion to cause an emergency brake application until the rate of release of fluid under pressure from the train brake pipe is increased to that of an emergency rate.